Embossing, in which a specific location of a base material is mechanically deformed by pressing from the back to the front, is known as one technology used to form letters, figures, symbols, graphics, etc., having a thickness of 0.2 mm or more, such as Braille characters for persons with vision or hearing disabilities, card numbers and names, on the surface of cards and other base materials.
However, in the case of technology in which letters and so forth having a thickness of 0.2 mm or more are formed by embossing, since it is necessary to mechanically deform the base material, together with there being restrictions on the material of the base material used, there is the risk of damaging the base material when performing embossing. In addition, although so-called IC cards containing internal IC, wiring patterns and so forth have been developed in recent years, in the case of performing embossing on base materials like these, there is the risk of causing disconnection of the IC, wiring patterns and so forth contained within.
Therefore, thick film printing by screen printing has been employed in the past as a method for obtaining letters and so forth having a thickness of 0.2 mm or more without placing restrictions on the base materials used and without having an effect on the base material. In addition, thick film printing using an ink jet system has also been proposed in recent years.
In the case of screen printing, however, the upper limit on the film thickness that can be printed in a single printing is several micrometers to several tens of micrometers, thereby resulting in the problem of being unable to obtain a thick film of 0.2 mm or more unless printing is repeated several times.
In addition, as an example of thick film printing using an ink jet system, Japanese Unexamined Patent Application, First Publication No. 2000-37943 discloses a method for performing thick film printing by an ink jet system using an ultraviolet curable ink having a surface tension greater than or equal to the wetting index of the printed base material. However, in the case of the method disclosed in Japanese Unexamined Patent Application, First Publication No. 2000-37943, it is difficult to obtain a stable thick film of the desired shape as a result of the shape of the coated ink being affected depending on the wetting index of the surface of the printed base material. In addition, in the case of thick film printing using an ink jet system, since it is difficult to discharge the ink unless the ink has a low viscosity as compared with screen printing, it is even more difficult to obtain a thick film.
In addition, since the photo-curable ink for thick film printing used in conventional thick film printing is required to be cured using an intense ultraviolet light source such as a mercury lamp, there is the risk of the base material being damaged by the ultraviolet light and heat. In addition, since ultraviolet radiation units using an intense ultraviolet light source such as a mercury lamp are large, a portable, compact printer for thick film printing has not been developed.